drm/nouveau: fix small thinko in vblank timestamping.
authorMario Kleiner <mario.kleiner.de@gmail.com>
Wed, 19 Mar 2014 09:02:11 +0000 (10:02 +0100)
committerBen Skeggs <bskeggs@redhat.com>
Wed, 26 Mar 2014 04:08:23 +0000 (14:08 +1000)
commit6c3252bc83155ae69d78fefdc7458aa64d8a87db
tree4e8e3e270a4caef78068470262c2d8347b4ada01
parentdcd9262b3baf881285e9e0fd5459d54723cc992e
drm/nouveau: fix small thinko in vblank timestamping.

*hpos horizontal scanout position doesn't need to be corrected
to count the pixels between hactive end and htotal negative.
That is only needed for *vpos to count lines until end of
vblank for the vblank timestamping.

Use hpos as is without correction.

Removes occassional spikes in timestamps of up to 1 scanline
duration, thereby improves accuracy to about +/- 2 usecs instead
of +/- 12 usecs, wrt. true onset time as measured with high
precision equipment on NV-A5.

Signed-off-by: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
drivers/gpu/drm/nouveau/nouveau_display.c